A multiport switch is a mechanical switch used to alter the path of an incoming signal at an input to one of several outputs, or to select one of several inputs for an output. Existing multiport switches operate up to a frequency of around 26.5 GHz. FIG. 1 shows an RF cavity housing 100 of a known single-pole-six-throw (SP6T) coaxial multiport switch (not shown). The RF cavity housing 100 has a starlike-shaped RF cavity 102 in a surface 104. The RF cavity 102 includes a central cavity 106 that defines a common port of the multiport switch. This central cavity 106 receives a centre pin of an RF connector (not shown). The RF cavity 102 also includes six troughs 108 that define six outer (individual) ports of the multiport switch. Each trough 108 receives the centre pin of a respective RF connector. The trough 108 is connected, at its proximal end 110, to the central cavity 106 to allow the centre pins in the trough 108 and the central cavity 106 to be electrically connected via a switch blade (reed) in a closed state of that port. At the distal end 112 of each trough 108 is a terminating load card to which the centre pin in the trough 108 is connected when in an open state of the port.
When covered using a cover (not shown), the trough 108 defines a channel with its proximal end connected to the central cavity 104. The width of the trough 108, and thus the channel, reduces at the proximal end 110 of the trough 108 towards the central cavity 106. The height of the channel at the proximal end 110 is equal to the height of a portion 114 of the channel immediately adjacent the proximal end 110. That is, the distance between opposing surfaces of the RF cavity housing 100 and the cover at the proximal end 110 is the same as the corresponding distance at the channel portion 114 immediately adjacent the proximal end 110.
Multiport switches having the above described RF cavity 102 are able to operate up to frequencies around 26.5 GHz. Examples of multiport switches having such an RF cavity 102 are two products (part numbers R594F73627 and R574F53400 respectively) from the microwave component manufacturer Radiall SA. However, military, aerospace and space environment applications require a multiport switch that is able to operate at frequencies higher than 26.5 GHz, for example, in the frequency range of 40-50 GHz.